• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.6
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• pp.1446-1454
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• 1990

A systematic method of design modification to reduce the influence of impact from multiple clearances in a planar four bar mechanism is developed. For this purpose, an optimization method is used with the objective function which is the linear sum of the Earles and Wu criteria for every joints with clearances. One coil spring is attached to a joint of limited range of revolution to reduce the undesirable dynamic effects due to clearances at joints. The stiffness of the coil spring and its pre-loading angle are chosen as design variables. A numerical example is taken for a four bar mechanism. The initial and modified mechanisms are compared using a clearance mechanism analysis technic to see the difference in dynamic effects due to contact loss. It is found that the modified mechanism produces much more smooth joint contact forces than the original design.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.6
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• pp.7-13
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• 1999

The unbalanced heavy-loaded elevation-driving system is composed of link-mechanism, hydraulic cylinder and compensator for the static unbalanced moment of the load. Control and compensation of elevation-driving system is very difficult because these mechanisms imply highly nonlinear properties due to hydraulic fluid characteristics and mechanical rotation of link-mechanism. In this study, through the analysis of the link-mechanism, the optimal design of the link-mechanism is suggested. Also to estimate the control performance of the unbalanced, heavy-loaded servo-controlled system, modeling and simulation of nonlinear system are carried out. To prove the validity of performance estimation program, simulation results are compared with the experimental results. Both results are similar, therefore this program will be helpful to study the improvement of the system control performance.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.5
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• pp.910-923
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• 1992

Experimental verification of numerical results is conducted by measuring the dynamic strains of mid-points of the coupler and the lever for the 4-bar linkage mechanism with rigid bearing and flexible bearing, respectively. For the axial strain of lever mid-point, the numerical results including geometric stiffness almost agree with the experimental ones, however, the numerical results excluding geometric stiffness almost agree with the experimental ones for the axial strain of coupler mid-point. It is supposed that these phenomena should be caused by the fact that the motion of the coupler is more complicated than of the lever. The signals of dynamic strains of coupler and lever mid-points, measured by strain gages, are transformed into frequency domain by fast fourier transformer. From this experiment, the lst resonance frequencies of the coupler and the lever are obtained. It is made clear that the former almost agrees with the fundamental and the latter the 2nd mode natural frequency of the mechanism system calculated by numerical analysis.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.5 s.122
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• pp.415-426
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• 2007

In a link motion punch press, numerous links are interconnected and each link executes a constrained motion at high speed. As a consequence, dynamic unbalance force and moment are transmitted to the main frame of the press, which results in unwanted vibration. This degrades productivity and precise stamping work of the press. This paper presents an effective method for reducing dynamic unbalance in a link motion punch press based upon kinematic and dynamic analyses. Firstly, the kinematic analysis is carried out in order to understand the fundamental characteristics of the link motion mechanism. Then design variable approach is presented in order to automate the model setup for the mechanism whenever design changes are necessary. To obtain the inertia properties of the links such as mass, mass moment of inertia, and the center of mass, 3-dimensional CAD software was utilized. Dynamic simulations were carried out for various combinations of design changes on some links having significant influences on kinematic and dynamic behavior of the mechanism.

• Proceedings of the KIEE Conference
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• 2003.11b
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• pp.7-10
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• 2003

뱀형 로봇은 자유도보다 액추에이터의 수가 적은 논홀로믹 구속조건(nonholonomic constraint)을 가지며, 단순한 신체구조 이지만 초-여유자유도 구속조건(hyper-redundant constraint)을 이용해서 기밀한 운동과 다양한 기능을 만들어내는 특징을 가지고 있다. 본 논문에서는 6개의 관절로 각 링크가 2차원 상에서 직렬로 연결된 뱀형 로봇의 기구설계 및 기구학과 동력학을 바탕으로 설계된 기구에 대해 해석하여 운동방정식을 유도하여 추진원리와 운동원리에 관하여 알아본다. 기본적인 운동 메커니즘을 해석하여 구현한 알고리즘을 제작한 로봇에 적용하여 추진 원리와 운동원리를 검증한다. 실험용 로봇은 링크 중앙에 법선 방향으로 마찰력이 발생할 수 있도록 수동바퀴를 가지고 있으며, PC와 RF(Radio Frequency)로 직렬통신을 하며 PC에서의 운동 명령의 조작에 의해 전진, 후진, 좌/우 방향으로 회전을 할 수 있도록 운동 알고리즘을 적용할 수 있도록 제작되었다. 특징으로는 일반적으로 토크를 입력으로 하지 않고 각도를 입력으로 하여 관절을 제어하고 있다는 점이 있으며, 운동방정식 또한 이에 대한 관계를 바탕으로 유도한 것이다.

• Proceedings of the Korean Fiber Society Conference
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• 2001.10a
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• pp.147-150
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• 2001

더블 라셀기(Double Raschel Machine)는 레이스와 메리야스 직물 등을 생산하기 위한 섬유기계로써 대부분의 섬유기계들이 그러하듯이 수많은 링크와 기구들로 이루어져 있다. 따라서, 이러한 복잡한 링크들로 이루어진 기계 구조물을 국산화 개발하기 위해서는 설계오류에 따른 수많은 시행착오와 시간이 소요된다. (중략)

• Current Industrial and Technological Trends in Aerospace
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• v.4 no.2
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• pp.13-24
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• 2006

국제민간항공기구(ICAO)의 차세대 항행시스템(new CNS/ATM) 전환계획에 따라 전 세계적으로 항공통신, 항법, 감시 및 항공교통관리 분야의 항행안전시설과 대응되는 항공기 탑재시스템의 변화가 진행되고 있다. 특히 항공통신과 감시 분야에서는 공대지 데이터링크 기술을 활용한 새로운 항공교통서비스(CPDLC, ADS, ADS-B, FIS-B, TIS-B)가 도입되어 공역 처리능력을 제고하고 항공운항 안전에 기여하며 조종사와 관제사의 편의성을 대폭 향상시킬 것으로 기대되고 있다. 현재 민간항공에서 활발히 이용되고 있는 대표적인 데이터링크 기술인 ACARS 시스템은 국제민간항공기구가 표준화하여 제정한 VDL 기술로 대체되고 있으며 HFDL, Mode S, AMSS, UAT 등이 현재 가용한 데이터링크 기술로 개발되어 활용되고 있다. 미국과 유럽을 중심으로 관련 기술에 대한 검증과 시범 운용 사업이 활발하게 진행되고 있으며 2020년 이후를 대비한 미래 항공통신 신기술 연구에도 세계가 매진하고 있다. 본 논문에서는 현재까지 개발된 공대지 데이터링크 기술의 특성을 개관하고 관련 응용기술 구현 현황과 데이터링크 관련 세계의 미래 통신기술 연구 동향을 제시하고자 한다.

• Aerospace Engineering and Technology
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• v.4 no.1
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• pp.25-30
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• 2005

The 4-bar linkage is the simplest model for the simulation of a retractable landing gear. In general, a designer uses a commercial software to design a linkage, which requires tedious iterations to obtain a good solution. By applying synthesis methodology the iteration process can be reduced remarkably. However, most of solutions obtained using synthesis process may not be an optimized solution. In this study, the characteristics of the optimization solution domain has been analyzed so that an optimization process can be adapted easily to a synthesis process.

• Journal of Power System Engineering
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• v.12 no.4
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• pp.64-71
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• 2008

This study is on pedestrian protection device using pneumatic cylinder and simple link mechanism when vehicle collide with pedestrian. This study ensured the safety space between engine and hood after it applies to simple link mechanism and pneumatic cylinder. It can absorb the damage which measure the specific device if vehicle collide with pedestrian. Combination of simple link mechanism and pneumatic cylinder was more superior than the present pedestrian protection device. Simple link mechanism could confirm superior height and survival probability than when only cylinder operated. It also ensured enough space between engine and hood. And if a cylinder is not working because of old cylinder, poor repair or damage of accident vertical cylinder would be difficult to execute because there exists the irregular space between engine and hood. If simple link mechanism operates with only one cylinder it could ensure the regular space because simple link mechanism set up at the middle of hood. So this device could confirm high safety for pedestrian.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.5
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• pp.2031-2037
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• 2011

The French doors have the advantage that they can use inner space more efficiently due to without of partition between two rooms. However, when they are used for refrigerators, the door gaskets for sealing may cause interference of themselves during opening and closing, which causes fatal effect on sealing by worn out of the gaskets as well as increases door opening force. This research proposes a new mechanism for the French doors using the parallelogram motion of 4-bar linkage mechanism, which does not make any interference between gaskets. We manufactured the French doors of proposed mechanism to verify that they do not cause any interference during opening and closing, as well as opening force is decreased. The use of our developed mechanism is not limited to refrigerators, but can be extended to other industrial products with the French doors.